Microsoft

Get IT Done: Speed up the Windows NT paging file

Tweak the Microsoft Windows NT page file to improve performance


TechRepublic member Tawana T. recently posted the question, “Is there a list of recommended page file sizes for larger hard drives, i.e., 36-GB hard drive?” She received several great responses that answered her query. (Way to go, TechRepublic members! Check out Tawana's question and the responses she received.) Because of Tawana’s interest and the fact that Windows 2000 won’t totally replace NT 4.0 for a few years, here is a little background information as well as some tips to help you speed up the NT paging file.

What is the paging file?
Windows NT utilizes hard disk space to increase the available memory for the system. The Virtual Memory Manager (VMM) manages the paging file by swapping pages from physical RAM to the paging, or swap, file stored on a hard drive. The name of the paging file is PA. The VMM automatically controls the paging file, but you can specify its size and location hard drive.
While the paging file can be spread across multiple drives, remember that the speed of Windows NT is largely determined by how fast the VMM can swap pages from physical RAM to the paging file. Therefore, place the paging file on your fastest physical drive(s).
How big is big enough?
How big should your paging file be? Microsoft recommends that the minimum size of your page file should be the amount of your machine’s physical RAM plus 12 MB. So if your computer has 128 MB of RAM, your page file should be at least 140 MB. While this formula is adequate, I would recommend a more generous size of 1.5 times the amount of your physical RAM. Therefore, if your machine has 128 MB of RAM, the minimum page file should be 192 MB. With today’s large, inexpensive hard drives, this should not be a problem for most systems.

Altering the page file
To alter the Windows NT paging file; open the Control Panel, double-click System, click the Performance tab, and click the Change button under the Virtual Memory section. From the Virtual Memory window, you can change the size of the paging file (see Figure 1).

Figure 1
Virtual Memory dialog box


There are two settings that you can specify for the paging file: “initial size” and “maximum size.” These parameters control exactly what their names imply. The “initial size” is the minimum amount of hard disk space the VMM will allocate for the page file, while the maximum size is the most. However, you must ensure your hard drive has enough available free space to comfortably accommodate the page file’s upper limit.
As a general rule, try to keep at least 100 MB of free hard drive space above and beyond what you’re using for the paging file. Windows NT will have problems if the maximum limit of your paging file is 200 MB and you only have 100 MB of free hard drive space.
Tips to speed up the paging file
  • Make the paging file large enough to handle the applications you’re running. (See the section on altering the page file.)
  • If you have multiple hard drives, you can spread the page file across these disks.
  • Move the paging file off the drive that contains the Windows NT system files. This prevents that paging file from competing with the NT operating system files.
  • Place the paging file on a faster hard disk.

Wrapping up
Use these tips as an inexpensive way to improve system performance before upgrading your hardware. However, if your computer’s performance is still slow even after increasing the page file size or moving it to a faster hard drive, your only options may be adding additional physical RAM or a faster CPU. Unfortunately, there is only so much the paging file can do.
Do you have any additional pointers that can make the Windows NT paging file work even better? We’d like to hear about them. Post a comment below or send us an e-mail.

About

Bill Detwiler is Managing Editor of TechRepublic and Tech Pro Research and the host of Cracking Open, CNET and TechRepublic's popular online show. Prior to joining TechRepublic in 2000, Bill was an IT manager, database administrator, and desktop supp...

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